Kelsea Ballerini still shudders at the memory of her very first show with a full band.

“It was New Year’s Eve 2014 going into 2015 at a casino in Reno [Nevada] for 12 people, who weren’t there to see me—they were there to party for New Year’s,” says Kelsea, recalling the show in vivid detail. “There was a mechanical bull by the stage and every time someone would get on or off of it, it would ding through our speakers and cut us off. And the cherry on top, by the end of our hour and a half set—it was a lot of covers because no one knew my songs yet—these two strippers came out and started stripping during the last four songs. We had no idea. I just remember walking offstage and thinking, ‘I don’t think I can do that every night.’ I was so discouraged.”

What a difference a year makes.

“Fast forward to this New Year’s Eve and I got to play in Nashville [at the Bash on Broadway] for 150,000 people,” she says, her eyes brightening at the more recent and much more pleasant memory. “To me, that’s my moment of perspective. From 12 people to that—that’s a crazy and amazing year.”

So crazy and amazing, Kelsea is hard-pressed to pick a single high point from 2015.

Chatting backstage before a late January show in Boston, the Knoxville-bred singer-songwriter remains incredulous about a banner year in which she experienced so many crucial firsts in her career, making her debut album title “The First Time” particularly apt.

The 22-year-old hit No. 1 with her sassy debut single “Love Me Like You Mean It”—the first female artist to achieve that feat since Carrie Underwood in 2006. She heard her name called as a nominee for several awards, including a CMA, an AMA and a CMT. She stepped into the venerated circle on the stage at the Grand Ole Opry. And she played her first headlining club tour, including this sell-out show in Boston. The crowd—from little girls to grandparents—stretched around the block for a chance to check out Kelsea and her rocking three-piece band play hits like “Love Me Like You Mean It” and the flirty second single “Dibs,” currently earmarking a spot in the top 10.

Seeing a picture of the epic line snaking down the street hours before show time, the bubbly Kelsea claps her hands together with delight and shouts, “Oh my gosh, that’s so cool!”

“I don’t have a pinnacle moment because there are so many that have happened that I still can’t even believe happened,” she says with a laugh, hanging in her dressing room as the audience fills up the club downstairs. “Firsts are special and it’s nice because I really didn’t know what being an artist was like until I got to do it for the first time this time. I was very naïve, I think, and it’s been a really big blessing because I wasn’t too scared of anything. I went into it open-minded and it’s been a really fun experience that way.”

Her eyes now turn towards taking that momentum and conquering 2016 in a similar fashion. Kelsea, who co-wrote all 12 tracks on The First Time, is especially looking forward to showing another side to her personality.

“I think people might have me pegged for this super poppy, happy-go-lucky, flirty, young girl that maybe just does what people tell me to do but that’s not the case,” says Kelsea. “I’m 22 and that’s definitely a part of me, but I’m excited to start sharing different corners of me that are on the record that people might not have heard yet.”

That starts with her ruminative third single, “Peter Pan.”

“It’s my favorite song on the whole record and it’s the song that, as a songwriter, lyrically, I’m really, really proud of,” she says of the ode to the boys who never seem to grow up into men. “I was so happy to lead with these first two singles and they’re easy to listen to, but with this one I hope people are like, ‘Oh wait, I actually want to listen to the words and I want to know what she has to say.’”

She’s also excited to hit the road this spring and summer on tours with Billy Currington and Rascal Flatts, respectively. The vocal trio in particular is one of her favorite bands, so much so that Kelsea performs a version of the Rascal Flatts’ hit “What Hurts the Most” in her set.

“We had a couple of tours that we were looking at joining, but I grew up going to Flatts shows,” she says. “The thing that I love the most about them is they have been so relevant, effortlessly, through decades of country music and they do it gracefully, and I want to learn how to do that.”

Toward that end, Kelsea is already at work on her sophomore album, writing when she can, (see sidebar) and she is excited to be a part of such a diverse freshmen class of country musicians who broke through in a big way in 2015.

“The Sam Hunts of the world and the [Chris] Stapletons and me and Cam, I feel like we’re all somehow blazing this new trail of country music together, but we’re all so different,” she says of her fellow hit-makers and buzz-worthy acts. “It’s been really fun to do it at the same time but all do our own thing at the same time. And I really respect all of them and what they do.”

The success Kelsea is experiencing now is all the sweeter since it comes after that less-than-inspiring start to 2015. Her advice to any artist in a similar situation currently is to commit to the moment and learn from it.

“Over the last year there were shows that were not good shows and not a lot of people came and I remember hearing the advice, “Focus on one person’” she says. “I was thinking, I’m going to sing ‘Forever and Ever, Amen’ because I think that one guy will enjoy that and that helped me get through it.”

And now Kelsea is excited for a new year, one free of mechanical bulls and filled with more firsts.

Yeah, Girl

Although she is just now releasing her third single, Kelsea is already starting to work on the follow-up to her debut album, The First Time. “I want to stay ahead of it and I just don’t want to rush it,” she says of the writing sessions that happen on the road with her producer Forest Glen Whitehead.

She’s also specifically setting aside time to write with female songwriters, both in Nashville—including a session with hit maker Lori McKenna (“Girl Crush,” “I Want Crazy”)—and out of town.

“My favorite thing is we’ll find a three day chunk of time and I’ll just pick three or four people and we’ll go to the beach or to a cabin and make the point of the trip to write songs which is my favorite headspace to get into.”

A 2015 excursion to Rosemary Beach in Florida with a clutch of songwriter pals, including Nicolle Galyon (“Automatic,” “God Made Girls”) and Jessi Alexander (“I Drive Your Truck”), yielded potential songs and a nice respite. “I was in a place where, I wasn’t sick of dudes, exactly, but I just wanted it to be girls,” she says with a laugh. “I think we’re going to do another one coming up in the next few months.”